to visit someone casually without prior arrangement
事前に取り決めなくカジュアルに誰かを訪ねること (jizen ni torikimenu kaku kajuaru ni dareka o tazuneru koto)
"My neighbors often drop in for coffee in the evening."
"私の隣人はよく夜にコーヒーを飲みにドロップインします。" (Watashi no rinjin wa yoku yoru ni kōhī o nomi ni **doroppu in** shimasu.)
to share laughter and happiness with someone
to impose strict security controls on something
to organize or structure code clearly
to resolve an issue directly with someone
to say something unintentionally
to stop rising or falling and become stable
